US8401740B2 - Adaptive energy absorption system for a vehicle seat - Google Patents
Adaptive energy absorption system for a vehicle seat Download PDFInfo
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- US8401740B2 US8401740B2 US12/661,435 US66143510A US8401740B2 US 8401740 B2 US8401740 B2 US 8401740B2 US 66143510 A US66143510 A US 66143510A US 8401740 B2 US8401740 B2 US 8401740B2
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Images
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60N—SEATS SPECIALLY ADAPTED FOR VEHICLES; VEHICLE PASSENGER ACCOMMODATION NOT OTHERWISE PROVIDED FOR
- B60N2/00—Seats specially adapted for vehicles; Arrangement or mounting of seats in vehicles
- B60N2/24—Seats specially adapted for vehicles; Arrangement or mounting of seats in vehicles for particular purposes or particular vehicles
- B60N2/42—Seats specially adapted for vehicles; Arrangement or mounting of seats in vehicles for particular purposes or particular vehicles the seat constructed to protect the occupant from the effect of abnormal g-forces, e.g. crash or safety seats
- B60N2/4207—Seats specially adapted for vehicles; Arrangement or mounting of seats in vehicles for particular purposes or particular vehicles the seat constructed to protect the occupant from the effect of abnormal g-forces, e.g. crash or safety seats characterised by the direction of the g-forces
- B60N2/4242—Seats specially adapted for vehicles; Arrangement or mounting of seats in vehicles for particular purposes or particular vehicles the seat constructed to protect the occupant from the effect of abnormal g-forces, e.g. crash or safety seats characterised by the direction of the g-forces vertical
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60N—SEATS SPECIALLY ADAPTED FOR VEHICLES; VEHICLE PASSENGER ACCOMMODATION NOT OTHERWISE PROVIDED FOR
- B60N2/00—Seats specially adapted for vehicles; Arrangement or mounting of seats in vehicles
- B60N2/24—Seats specially adapted for vehicles; Arrangement or mounting of seats in vehicles for particular purposes or particular vehicles
- B60N2/42—Seats specially adapted for vehicles; Arrangement or mounting of seats in vehicles for particular purposes or particular vehicles the seat constructed to protect the occupant from the effect of abnormal g-forces, e.g. crash or safety seats
- B60N2/427—Seats or parts thereof displaced during a crash
- B60N2/42727—Seats or parts thereof displaced during a crash involving substantially rigid displacement
- B60N2/42736—Seats or parts thereof displaced during a crash involving substantially rigid displacement of the whole seat
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60N—SEATS SPECIALLY ADAPTED FOR VEHICLES; VEHICLE PASSENGER ACCOMMODATION NOT OTHERWISE PROVIDED FOR
- B60N2/00—Seats specially adapted for vehicles; Arrangement or mounting of seats in vehicles
- B60N2/24—Seats specially adapted for vehicles; Arrangement or mounting of seats in vehicles for particular purposes or particular vehicles
- B60N2/42—Seats specially adapted for vehicles; Arrangement or mounting of seats in vehicles for particular purposes or particular vehicles the seat constructed to protect the occupant from the effect of abnormal g-forces, e.g. crash or safety seats
- B60N2/427—Seats or parts thereof displaced during a crash
- B60N2/42772—Seats or parts thereof displaced during a crash characterised by the triggering system
- B60N2/4279—Seats or parts thereof displaced during a crash characterised by the triggering system electric or electronic triggering
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60N—SEATS SPECIALLY ADAPTED FOR VEHICLES; VEHICLE PASSENGER ACCOMMODATION NOT OTHERWISE PROVIDED FOR
- B60N2/00—Seats specially adapted for vehicles; Arrangement or mounting of seats in vehicles
- B60N2/50—Seat suspension devices
- B60N2/501—Seat suspension devices actively controlled suspension, e.g. electronic control
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60N—SEATS SPECIALLY ADAPTED FOR VEHICLES; VEHICLE PASSENGER ACCOMMODATION NOT OTHERWISE PROVIDED FOR
- B60N2/00—Seats specially adapted for vehicles; Arrangement or mounting of seats in vehicles
- B60N2/50—Seat suspension devices
- B60N2/502—Seat suspension devices attached to the base of the seat
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60N—SEATS SPECIALLY ADAPTED FOR VEHICLES; VEHICLE PASSENGER ACCOMMODATION NOT OTHERWISE PROVIDED FOR
- B60N2/00—Seats specially adapted for vehicles; Arrangement or mounting of seats in vehicles
- B60N2/50—Seat suspension devices
- B60N2/52—Seat suspension devices using fluid means
- B60N2/522—Seat suspension devices using fluid means characterised by dampening means
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F15/00—Suppression of vibrations in systems; Means or arrangements for avoiding or reducing out-of-balance forces, e.g. due to motion
- F16F15/002—Suppression of vibrations in systems; Means or arrangements for avoiding or reducing out-of-balance forces, e.g. due to motion characterised by the control method or circuitry
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F9/00—Springs, vibration-dampers, shock-absorbers, or similarly-constructed movement-dampers using a fluid or the equivalent as damping medium
- F16F9/32—Details
- F16F9/53—Means for adjusting damping characteristics by varying fluid viscosity, e.g. electromagnetically
Definitions
- the present invention relates generally to energy absorbers and energy absorption systems, and more particularly to shock and vibration energy absorption systems for vehicle seats for mitigating occupant injury due to extreme vehicle movement (e.g., during a vehicle shock event), and/or for mitigating vibration experienced by an occupant of the vehicle seat during normal vehicle operating conditions.
- a seat suspension system can be used to mitigate the vertical shock loads that are transmitted from the base of the vehicle (or extension thereof), and imparted into the human body.
- the attenuation of vertical impact forces in vehicle mishaps is one of the prime factors in determining survivability.
- Energy absorbers also known as energy attenuators or load limiters
- load limiters are a key component of crashworthy seat designs.
- Energy-absorbing crew seats for helicopter applications have made significant improvements in helicopter crash survival.
- Early crashworthy crew seats used fixed-load energy absorbers (FLEAs) to limit the load on an occupant's spine.
- FLEAs fixed-load energy absorbers
- One drawback associated with these FLEAs is that they were not adjustable and stroked at a factory-established, constant load throughout their entire operating range.
- VLEAs Variable load energy absorbers
- a VLEA enables an occupant to manually adjust the constant stroking load by setting a control (e.g., a dial) to the occupant's weight.
- the load increases for large occupants, for example, taking advantage of their greater spinal load tolerance to reduce the stroked distance. By contrast, the load decreases for smaller occupants to reduce the risk of injury to their weaker spines.
- a VLEA enables a seat to deliver the same low-injury risk regardless of occupant weight. VLEAs were developed with a provision so that a wide range of occupants would have equal protection in a crash.
- An energy absorber load is selected that is proportional to the occupant's weight so that each occupant will experience similar acceleration and use similar stroking space in a crash.
- FPEAs fixed profile energy absorbers
- FPEAs fixed profile energy absorbers
- One drawback associated with FPEAs is that they are passive, meaning that they cannot adapt their energy absorption or stroking profiles as a function of occupant weight, or as a function of real-time environmental measurements such as a crash velocity, vibration or shock load. These variables are essential if vibrations and/or impact energy is to be absorbed most efficiently.
- Seat suspension systems that utilize FPEAs suffer from these and other drawbacks.
- an adaptive energy absorption system for a vehicle seat utilizing an adaptive energy absorber or variable profile energy absorber (VPEA) for mitigating injury due to extreme vehicle movement (e.g., during a vehicle shock event), and/or for mitigating vibration, over a wide range of occupant weights and load levels.
- VPEA variable profile energy absorber
- the adaptive energy absorption system comprises a VPEA, a controller (e.g., a single-mode or multi-mode controller), and one or more sensors for indication and/or measurement of surrounding stimuli, including extreme motion “shock events.”
- the VPEA responds to changing environmental stimuli such as occupant weight, occupant attitude, load level, or other stimuli, to effectively mitigate loads into the occupant's body.
- the VPEA may be automatically adjusted in real-time to minimize occupant motion based upon a known occupant weight (e.g., automatically sensed or manually adjusted) and known vibration levels (e.g., from sensors).
- Limiting seat motion provides the advantages of enhancing comfort and reducing fatigue for the occupant of the vehicle seat.
- motion sensors may trigger the controller into a secondary mode, wherein the VPEA may be automatically adjusted to keep body loads (pelvic loads, spinal loads, etc.) within acceptable levels.
- An optional fixed profile energy absorber FPEA may also be included, the variable profile energy absorber and the fixed profile energy absorber configured to be in series to mitigate vibration and shock.
- VPEA is herein defined as any suitable device used to absorb energy by providing a controlled resistive force applied over a deformation distance without significant elastic rebound, and for which the controlled resistive force can be continuously adjusted over that over a deformation distance.
- Suitable VPEAs may comprise any of an active valve damper, a magnetorheological fluid damper, an electrorheological fluid damper, a magnetic energy absorber, and a servo-hydraulic actuator.
- Active valve dampers are pneumatic or hydraulic cylinders that rely on internal valving changes to automatically adjust their damping effect.
- Active valve dampers with electrically controlled damping constants are known in the art, and typically use variable valve orifices to adjust the damping force.
- a magnetorheological fluid damper is a damper filled with magnetorheological fluid, which viscosity is controlled by a magnetic field, usually using an electromagnet. This allows the damping characteristics of the shock absorber to be continuously controlled by varying the power of the electromagnet.
- Magnetorheological fluid dampers are likewise known in the art and available, for example, from the Lord Corporation of Cary, N.C.
- An electrorheological fluid damper is a damper filled with electrorheological fluid, which viscosity is controlled by electric an electric field applied to the fluid.
- Fludicon GmbH markets various standard and custom electrorheological fluid dampers.
- ER and MR fluids possess the ability to change properties when electric or magnetic fields are applied there across, respectively. This change is mainly manifested as a substantial increase in dynamic yield stress, or apparent viscosity, of the fluid. ER and MR fluids exhibit nonlinear effects due to applied field, applied loads, strain amplitude, and frequency of excitation in dynamic displacement conditions.
- ER & MR damper The application of ER & MR fluids to the valve of a damper in the presence of a controllable electric/magnetic field results in the semi-active device known as an ER & MR damper, respectively.
- a variety of magnetic energy absorbers have been developed and are known in the art including cylindrical-type electromagnetic actuators that use magnetic fields from electromagnets to apply damping to a structure.
- a servo-hydraulic actuator employs a hydraulic cylinder-type actuator controlled by a servo motor.
- the VPEA responds to changing environmental stimuli such as occupant weight, occupant attitude, load level, or other stimuli, to effectively mitigate loads into the occupant's body.
- the VPEA may be automatically adjusted in real-time to minimize occupant motion based upon a known occupant weight (e.g., automatically sensed or manually adjusted) and known vibration levels (e.g., from sensors).
- Limiting seat motion provides the advantages of enhancing comfort and reducing fatigue for the occupant of the vehicle seat.
- an extreme motion event e.g., a shock event
- motion sensors may trigger the controller to automatically adjust the VPEA to keep body loads (pelvic loads, spinal loads, etc.) within acceptable levels.
- an optional fixed profile energy absorber FPEA may also be included, the VPEA and FPEA being configured in series to mitigate vibration and shock.
- the present invention expands the concept by providing the capability of responding to more than one (e.g., repetitive) shock event.
- the general system components, architecture, and function are the similar and the present system likewise employs an adaptive seat energy absorption system that utilizes a variable profile energy absorber (VPEA) to prevent bodily injury during a shock event.
- VPEA variable profile energy absorber
- the present system employs a dual mode operation. When operating in primary mode during normal operating conditions (non-shock event) the system functions to minimize occupant motion based upon a known occupant weight (e.g., automatically sensed or manually adjusted) and known vibration levels (e.g., from sensors). Limiting seat motion provides the advantages of enhancing comfort and reducing fatigue for the occupant of the vehicle seat.
- the present system automatically switches to and functions in secondary mode during severe (shock event) operation, and automatically adjusts in real-time to keep loads transmitted to the occupant's body below acceptable injury threshold levels, and can recover to perform said function for multiple shock events.
- the present invention is an adaptive energy absorption system for a vehicle seat that functions in dual-modes, including a primary mode during normal (non-shock event) operation, and secondary mode during severe (shock event) operation.
- primary mode When operating in primary mode the system reduces vehicle vibration transmitted to the occupant, thereby reducing fatigue and increasing situational awareness.
- secondary (shock) mode the present system automatically adjusts a VPEA in real-time to keep loads transmitted to the occupant's body below acceptable injury threshold levels, and can recover to perform this function for multiple shock events.
- the present system employs a VPEA connected between the vehicle seat and a supporting structure such as the vehicle frame.
- a controller e.g., a single-mode or multi-mode controller, plus one or more sensors in communication with the controller for indicating and/or measuring surrounding stimuli, including extreme motion “shock events.”
- sensors e.g., a variety of different sensors are provided for measuring, among other things, force, acceleration, velocity, strain, displacement, etc.
- the sensors may be pre-existing vehicle sensors (e.g., an aircraft altimeter to measure sinkrate).
- the controller runs control software which monitors the sensor(s) and controls the VPEA in accordance therewith, based on a selectable control profile.
- the control software Based on the sensor-feedback loop, the control software automatically detects surrounding stimuli, including shock events, and selectively switches between a primary mode in which the control profile reduces vehicle vibration transmitted to the occupant, thereby reducing fatigue and increasing situational awareness, and a secondary mode during severe (shock event) operation in which the control profile keep loads transmitted to the occupant's body below acceptable injury threshold levels. Whilst in secondary mode the system can recover to perform the function for multiple shock events.
- the operational mode of the system is selected by the controller using measurement signals from at least one sensor, which also allows the system to automatically adjust change mode in real time to one of the two different control profiles, each a function of occupant weight.
- the adaptive energy absorption system may additionally comprise a conventional fixed profile energy absorber (FPEA) and/or a stiffness element (e.g., to supplement VPEA force and aid in vibration isolation) alone or in combination with the VPEA.
- FPEA fixed profile energy absorber
- stiffness element e.g., to supplement VPEA force and aid in vibration isolation
- one or more components of the adaptive energy absorption system may be powered by a power source independent of the vehicle (e.g., via one or more batteries). The independent power source enables the system to continue to function in the event of a loss of vehicle power due to, for example, a shock event, or for any other reason.
- the VPEA may respond to changing environmental stimuli such as occupant weight, occupant attitude, load level, or other stimuli, to effectively mitigate loads into the occupant's body.
- the VPEA may be automatically adjusted in real-time to minimize occupant motion based upon a known occupant weight (e.g., automatically sensed or manually adjusted) and known vibration levels (e.g., from sensors).
- Limiting seat motion provides the advantages of enhancing comfort and reducing fatigue for the occupant of the vehicle seat.
- an extreme motion event e.g., a shock event
- motion sensors may trigger the controller into its secondary mode, wherein the VPEA may be automatically adjusted to keep body loads (pelvic loads, spinal loads, etc.) within acceptable levels.
- the controller may automatically adjust the VPEA in real-time to optimize occupant body loads based on a feedback control algorithm.
- sensors for measuring VPEA stroke e.g., Linear Variable Differential Transformers (LVDTs)
- LVDTs Linear Variable Differential Transformers
- accelerometers on the vehicle floor, vehicle seat, and/or occupant helmet (or other wearable article) may provide measurements which are fed back to the control algorithm.
- the control algorithm may then use this sensor data to maintain body loads (e.g., lumbar force, chest accelerations, etc.) below injury limits.
- body loads e.g., lumbar force, chest accelerations, etc.
- VPEAs have the ability to vary their load-stroke profile to account for occupant weight.
- the occupant weight may be determined by a manual setting, or via sensor measurement, and then used to automatically tune the system for the dynamics of the occupant as well as the occupant's injury criteria.
- statistical biodynamic data may be used to develop relationships between occupant weight, dynamic parameters, and injury criteria.
- the controller may use the aforementioned sensor data to determine occupant motion/loads and/or a mathematical biodynamic model (such as a lumped parameter model) to estimate occupant motion/loads in order to determine how to adjust the VPEA to maintain body loads below injury criteria. If a mathematical biodynamic model is utilized, dynamic parameters may be automatically updated based upon the occupant weight.
- the controller may use a gain schedule to adjust the VPEA in a pre-determined manner for given set parameters such as motion, weight, injury criteria, etc.
- Yet another advantage provided by the invention is the capability to adapt to varying shock input levels. Real-time environmental measurements may be used to tune the system to the harshness of each particular event. This is an advantage over conventional seat energy absorption systems which tend to be tuned for a fixed shock level (thus, not optimally controlling body loads for other shock levels).
- Still yet another advantage provided by the invention is that real-time feedback control may be used to optimally control the VPEA to mitigate vibration due to normal vehicle operation, thereby enhancing comfort and reducing fatigue for the occupant.
- the same controller used for shock control may be utilized for vibration control.
- a multi-mode controller may be used that minimizes occupant vibration during normal operation, and then switches to a shock control mode during an extreme motion event. Once an extreme motion event is measured, the controller may switch to a shock control mode to prevent occupant injury.
- the VPEA may be automatically adjusted in real-time to keep body loads (pelvic loads, spinal loads, etc.) within acceptable levels during a vehicle shock event (or other extreme motion event).
- a stiffness element e.g., a coil spring
- shock mitigation design however, a stiffness element is undesirable because it stores energy and provides a potentially injurious or even lethal rebound reaction into the occupant.
- the adaptive energy absorption system may be used with any type of vehicle seats including, but not limited to, aircraft seats, land vehicle seats, marine vehicle seats, or seats for other vehicles that may experience vertical (or other) shock loads (whether it be a one-time event or repetitive shock), or that may be exposed to varying levels of vibration during normal operating conditions.
- the adaptive energy absorption system may be integral with a vehicle seat, or retro-fit to existing vehicle seats.
- FIG. 1 is an exemplary illustration of an adaptive energy absorption system for a vehicle seat, according to an embodiment of the invention.
- FIG. 2 is an exemplary illustration of a sample MR damper design.
- FIG. 3 is an illustration of a graphical view showing force v. velocity with respect to damping at various applied currents.
- FIG. 4 is an illustration of a graphical view of hysteresis cycle with respect to displacement.
- FIG. 5 is a graphical view of a dynamic range of an adjustable damper which may be controlled.
- FIG. 6 is an exemplary illustration of a control-flow diagram, according to an aspect of the invention.
- FIG. 7 is an exemplary illustration of a control-flow diagram, according to an aspect of the invention.
- FIG. 8 is an exemplary illustration of a control-flow diagram, according to an aspect of the invention.
- FIG. 9 illustrates an adaptive energy absorption system for a vehicle bench seat.
- FIG. 10 illustrates an array of sensors ( 70 a , 70 b , . . . 70 n ) distributed throughout the vehicle near locations of high probability of shock onset.
- An adaptive energy absorption system is disclosed for use with any type of vehicle seats including, but not limited to, aircraft (e.g., rotorcraft, fixed wing, etc.) seats, land vehicle seats (e.g., seats for heavy-duty military, agricultural, and construction vehicles, etc.), marine vehicle seats, or seats for other vehicles that may experience vertical (or other) shock loads, or that may be exposed to varying levels of vibration during normal operating conditions.
- aircraft e.g., rotorcraft, fixed wing, etc.
- land vehicle seats e.g., seats for heavy-duty military, agricultural, and construction vehicles, etc.
- marine vehicle seats e.g., or seats for other vehicles that may experience vertical (or other) shock loads, or that may be exposed to varying levels of vibration during normal operating conditions.
- an adaptive energy absorption system 100 is provided for shock and vibration absorption to a vehicle seat 20 .
- Vehicle seat 20 may comprise an existing vehicle seat, and one or more of the components of system 100 (as disclosed herein) may be retrofit to vehicle seat 20 .
- vehicle seat 20 along with one or more components of system 100 may be provided together as an integral system for original installation in a vehicle.
- VPEA variable profile energy absorber
- a stiffness element 50 such as a spring, passive pneumatic or hydraulic cylinder or other FPEA, is operatively connected, preferably in parallel, between the vehicle seat 20 and the supporting structure of the vehicle for both shock mitigation and vibration isolation, as well as to recoil or rebound the system in preparation for subsequent shock event(s).
- VPEA 30 operates in conjunction with stiffness element 50 .
- the stiffness element 50 may have a fixed stiffness profile and may operate as a passive element, it may alternatively have a variable stiffness profile and function as a semi-active, or active element as described below.
- System 100 further comprises a programmable controller 60 capable of operating in at least a single mode (a secondary extreme motion mode), but more preferably operable in multi-mode (or dual modes) including a primary vibration control mode and the secondary extreme motion mode.
- Controller 60 includes memory for storing and running control software 62 that automatically adjusts VPEA 30 in real-time to an optimal setting based on feedback from a weight indication mechanism 72 and/or one or more sensors ( 70 a , 70 b , . . . 70 n ) which will be described in detail below.
- One or more components of system 100 may be powered by a power source 90 , as described in greater detail below, and one skilled in the art should understand that a single controller 60 may be used to control multiple VPEA 30 -equipped seats 20 .
- VPEA 30 responds to changing environmental stimuli such as occupant weight, occupant attitude, load level, or other stimuli, to effectively mitigate loads into the occupant's body.
- controller 60 may operate only in a secondary mode to mitigate injury to an occupant of vehicle seat 20 when an occurrence of a vehicle shock event (or other extreme motion event) is determined.
- controller 60 may be used to adjust VPEA 30 for purposes of both vibration isolation and shock mitigation.
- controller 60 may operate in a first (primary) mode to automatically adjust VPEA 30 in real-time to minimize occupant motion based upon a known occupant weight (e.g., automatically sensed or manually adjusted) and/or known vibration levels (e.g., from sensors).
- Limiting motion of vehicle seat 20 provides the advantages of enhancing comfort and reducing fatigue for the occupant of vehicle seat 20 .
- motion sensors may trigger controller 60 into a secondary mode, wherein VPEA 30 may be automatically adjusted to keep body loads (pelvic loads, spinal loads, etc.) within acceptable levels.
- FIG. 1 Prior to describing the various control strategies that may be implemented for vibration isolation and/or shock mitigation, an explanation of the one or more components that may comprise system 100 ( FIG. 1 ) will now be provided. It should be recognized, however, that one or more of the components of system 100 (depicted in FIG. 1 ) may or may not be present (or may be present in various configurations) in different implementations of the invention, depending on whether system 100 is utilized for vibration isolation and/or shock mitigation. Accordingly, the depiction of system 100 in FIG. 1 is exemplary only, and should not be viewed as limiting. Additional configurations of system 100 will be described below and illustrated in the accompanying drawing figures.
- one or more components of system 100 may be powered by a power source 90 .
- power source 90 may comprise a power source associated with the vehicle.
- power source 90 may comprise a source (e.g., one or more batteries) independent of the vehicle so as to enable system 100 to continue to function in the event of a loss of vehicle power due to, for example, a shock event, or for any other reason.
- one or more components of system 100 may be powered by a power source associated with the vehicle, while power source 90 serves as a “back-up,” independent power source which will activate upon a loss of vehicle power.
- Other configurations may be implemented.
- one or more sensors may be provided for indication and/or measurement of surrounding stimuli, including extreme motion “shock events” and/or real-time motion information.
- at least one sensor may be provided on vehicle seat 20
- one sensor may be provided on base 10 of the vehicle (e.g., on the floor of the vehicle, or on a platform or other structure to which vehicle seat 20 may operatively connected) so that the input load levels as well motion of the occupant (both absolute & relative) may be determined.
- sensors 70 a , 70 b , . . .
- sensors ( 70 a , 70 b , . . . 70 n ) may measure force (e.g, load cells), acceleration (e.g., accelerometers), velocity (e.g., PVTs, etc.), strain/displacement (e.g., LVDT, strain gauge, etc), deformation (e.g., a frangible wire or fiber-optic line that, when broken or bent, indicates the onset of shock, and optionally measuring it), vehicle position, and/or vehicle attitude.
- sensors ( 70 a , 70 b , . . . 70 n ) may comprise, or interface to, existing vehicle sensors (e.g., an aircraft altimeter to measure sinkrate). As seen in FIG. 10 , sensors ( 70 a , 70 b , . .
- . 70 n may be distributed throughout the vehicle near locations of high probability of shock onset, such as front or rear crumple zones, or at the four corners of the vehicle footprint (as shown) in an effort to enable sufficient time for the controller 60 to adjust, via a control signal, the adaptive energy absorption system prior to the shock event actually reaching the vehicle seat 20 and occupant, thereby establishing a type of preview control.
- a weight indication mechanism 72 is also used to obtain an occupant's weight (or mass) to tune the system to the occupant.
- weight indication mechanism 72 may comprise a manual control for enabling an occupant to manually select his or her weight
- a weight sensor is preferably positioned on vehicle seat 20 .
- Weight sensor 72 may be a strain gauge or other like mechanism for obtaining the weight of an occupant of vehicle seat 20 .
- PVDF sensors in (or associated with) vehicle seat 20 may be used to measure occupant center of gravity (CG).
- An array of proximity/position sensors in (or associated with) vehicle seat 20 may be used to determine body position, and an array of force or strain sensors in (or associated with) the structure of vehicle seat 20 may also be utilized to measure occupant CG. Additional implementations exist.
- one or more of sensors may be body-mounted such as, but not limited to, those mounted on a helmet, clothing, etc. of the occupant of vehicle seat 20 to measure real-time body loads.
- FIG. 1 Due to the numerous configurations and possible placement positions of one or more sensors ( 70 a , 70 b , . . . 70 n ), they have been illustrated generally in FIG. 1 . Various other types of sensors may be implemented as would be appreciated by those having skill in the art.
- controller 60 may comprise a processor, as well as a memory for storing control software 62 which comprises one or more control algorithms for execution by the processor.
- the memory also stores data that may be used and/or produced by execution of the one or more control algorithms.
- Controller 60 interfaces with, and receives measurement signals (controller inputs) from, one or more sensors ( 70 a , 70 b , . . . 70 n ) and/or weight indication mechanism 72 and/or sensor(s) 73 . Based on processing performed, controller 60 interfaces with, and generates one or more control signals (controller outputs) to control one or more components of system 100 (e.g., VPEA 30 ).
- controller 60 may comprise a single-mode controller that may operate only in a mode to mitigate injury to an occupant of vehicle seat 20 when an occurrence of a vehicle shock event (or other extreme motion event) is determined. Even where controller 60 is a single-mode controller, it may still function both to minimize vibration and optimize body loads during a vehicle shock event using common software 62 implementing a single software method. However, the present invention contemplates a fundamentally different cause-effect feedback loop for these two different types of operation, which requires fundamentally different software control, and so the preferred embodiment of the invention automatically adapts, switching from primary vibration control mode to extreme motion control mode when a severe shock event is detected. This is what is intended by ‘dual-mode’ or “multi-mode” controller 62 .
- controller 60 preferably comprises a dual-mode controller having a first control mode (which may be referred to herein as a primary normal or vibration control mode), and a secondary control mode (which may be referred to herein as a shock control mode).
- a single controller 60 may be used to control multiple VPEA 30 -equipped seats 20 .
- Each of the modes of controller 60 are discussed in greater detail below.
- VPEA Variable Profile Energy Absorber
- VPEA 30 may comprise any VPEA that can modify its energy absorbing capabilities as commanded by a feedback control system. Examples of such devices are noted above. Using feedback control, these dampers may adjust the load profile as vehicle seat 20 strokes, for example, during a crash or other vehicle shock event.
- MR and ER fluid dampers are advantageous because they are able to achieve what is effectively an infinitely adjustable profile energy absorber, as described below.
- MR fluid dampers are advantageous in that they are easily powered by a DC electrical supply (e.g., battery) which facilitates the provision of an independent power source (e.g., power source 90 ), as described above.
- a DC electrical supply e.g., battery
- an independent power source e.g., power source 90
- FIG. 2 (A &B) is an exemplary illustration of a suitable MR damper design found in U.S. Pat. No. 6,694,856 B1 (issued Feb. 24, 2004), entitled “MAGNETORHEOLOGICAL DAMPER AND ENERGY DISSIPATION METHOD” to Chen et al., which is hereby incorporated by reference herein in its entirety.
- An explanation of the operation of an MR damper will not be provided herein, as MR dampers are known and understood by those having skill in the art.
- FIG. 3 illustrates representative test data obtained from a COTS Lord RheoneticsTM. damper showing the force vs. piston velocity behavior as a function of applied field.
- the damper force can be broken into two regimes, preyield and postyield.
- the preyield portion tends to be fairly rigid and is often approximated as Coulomb damping, while the postyield is plastic and is often approximated as viscous damping.
- FIG. 4 illustrates representative force vs. piston displacement behavior for an MR damper.
- the total energy dissipated by the damper is represented by the area within the depicted hysteresis curves.
- the hysteresis loop increases in size, thereby increasing the amount of energy that can be dissipated by the damper.
- ER and MR dampers are purely dissipative. That is, there is only control authority when the desired force and the relative velocity are of the same sign. More specifically, ER and MR dampers have a dynamic range limited by the field-off and maximum field cases as shown in FIG. 5 .
- one or more VPEAs 30 may be utilized in system 100 , and their arrangement may vary. Multiple VPEAs 30 may be implemented in parallel, for instance, to increase the capacity. Using multiple VPEAs may also enable the use of smaller devices rather than one larger device. Additionally, arranging VPEAs in a diagonal configuration may be beneficial in maximizing stroke when vertical space is limited.
- system 100 may further comprise one or more stiffness or “spring” elements 50 operatively connected between the vehicle 10 and the seat 20 .
- the stiffness element 50 operates passively, semi-actively, or actively, and may have a fixed or variable stiffness profile.
- stiffness element 50 may include, but are not limited to, coil springs, leaf springs, visco-elastic material, or any spring or spring system having a natural harmonic frequency which, when a vibration frequency is applied, will resonate.
- Stiffness element 50 if used, may be implemented such that it provides a tuned stiffness for vibration control (preferably soft to reduce transmissibility). The tuning of this stiffness is important because its use may sacrifice some stroke of the VPEA 30 energy absorber(s) during a shock event.
- variable stiffness spring (vs. fixed stiffness) may be advantageous because it would enable tuning to varying occupant masses.
- the stiffness spring 50 may be variable, adjusted by a manual control mechanism (e.g., a dial), or automatically adjusted based upon an occupant mass measurement.
- the stiffness element 50 performs a recoil and recovery function to return the suspension system 30 to substantially its initial position.
- the recoil function returns the VPEA 30 to substantially its initial position after a first shock event quickly enough to perform its function for a subsequent shock event.
- the recovery function controls the recoil in such a way that the suspension system 30 does not experience an extensional end-stop impact, and so that the system does not oscillate undesirably.
- One example of a method for quickly returning the suspension system to its initial position without oscillation is to adjust the force level of the VPEA to provide substantially critical equivalent viscous damping during stroke recovery, though other methods and approaches may be suitable.
- the combined recoil/recovery function may be passive, implemented only by the resilient properties of the stiffness element 50 .
- the recoil/recovery function may also be active, entailing a feedback loop for coordinated control of the VPEA 30 and stiffness element 50 .
- the controller 60 may detect the occurrence of a first shock event (from a sensor)
- the magnitude of a second immediate shock event may be estimated based on prior collected sensor measurement data (e.g., severity of the first shock event).
- the controller 60 may communicate with the VPEA 30 via a control signal to mitigate the anticipated transmission of loads to the seat occupant at the predicted second shock level. This sequence may be repeated as needed. Once the occurrence of shock events has ceased, the controller 60 may then return the VPEA 30 to the primary operational mode for vibration isolation.
- a data logger 80 may be provided to store and record information related to the shock and/or vibration such as measurements thereof.
- the data logger 80 may be connected directly to the sensors 70 a - 70 n to log the sensor data in internal memory for later download to a computer.
- the data logger may also be embedded into the controller 60 itself, whereas the controller's microprocessor stores the sensor data or processed sensor data (i.e., filtered, mathematical operations, etc.) onto onboard memory, such as internal microprocessor memory, an on board hard drive, or other onboard memory (i.e, removable or non-removable solid state memory, removable media, etc).
- the data logger 80 and/or removable memory/media may also be connected to the controller 60 and/or in communication with a remote host computer 85 for analysis, evaluation, and/or storage of the data.
- the data may be analyzed to provide a vehicle and/or personnel dosimetry capability, in which logged shock and/or vibration data is used to keep record of vehicle and/or vehicle occupant exposure for health/maintenance purposes.
- the controller 60 may be programmed to compare sensor data to predetermined thresholds to determine shock events and/or vibration exposure exceeding defined limits.
- the controller 60 may in turn be in communication with remote host computer 85 , display console, or other device 85 , or may emit cellular or RF wireless signals as event notifications.
- the controller 60 may send remote host computer 85 a shock event notification, or an over-limit notification, wherein an identifiable indication that a system sensor 70 a . . . n has measured an event over a preset limit has occurred.
- the controller 60 may also signal such notifications over a connected audio and/or visual alarm 87 .
- the controller 60 may also send remote host computer, display console, or other device 85 a failure alarm, e.g., an identifiable indication that at least one component of the adaptive seat energy absorption system 100 is not working properly. All sensor and communication signals can be carried through wires, wirelessly, or any combination thereof.
- FIGS. 6-8 are exemplary control-flow diagrams for various implementations of the invention, wherein controller 60 operates as a dual-mode controller having a first control mode (e.g., a normal or vibration control mode), and a second control mode (e.g., a shock control mode).
- controller 60 may function to provide vibration isolation during normal vehicle operation, and may automatically switch to second (secondary) control mode to mitigate (or prevent) bodily injury to an occupant of vehicle seat 20 during a vehicle shock event, in real time based on signals from sensors ( 70 a , 70 b , . . . 70 n ) measuring surrounding stimuli that indicate extreme motion “shock events”.
- FIG. 6 is an exemplary illustration of a control flow diagram for the system 100 inclusive of control software 62 of FIG. 1 (and method), wherein controller 60 comprises a dual mode controller and supplies a different control to the VPEA 30 depending on whether the inputs are indicative of normal vehicle operation, or a shock event.
- control software 62 in controller 60 may comprise one or more of a motion determination module 620 , vibration mode module 624 , biodynamic model module 626 , shock mode module 628 , or other modules, each of which may enable the various functions that aid in vibration isolation and/or shock mitigation.
- One or more of the foregoing controller modules 620 - 628 may be combined. For some purposes, not all modules may be necessary.
- controller 60 receives real-time vehicle motion information via measurement signals (controller inputs) from one or more sensors ( 70 a , 70 b , . . . 70 n ) as described in detail above. Controller 60 may also receive occupant weight from weight indication mechanism 72 (manual control, weight sensors, or like mechanisms). In some implementations, controller 60 may utilize a fixed occupant weight value (e.g., the weight for a 50th percentile male) selected from any number of biodynamic data sources. Controller 60 may also receive attitude measurements via measurement signals (controller inputs) from one or more occupant attitude sensors.
- a motion determination module 620 determines whether the vehicle is operating under normal conditions, or whether a shock event (or other extreme motion event) is occurring. This determination is made by comparing one or more motion or load measurements (e.g., acceleration, force, etc.) to one or more predetermined values (or thresholds). If one or any combination of sensors ( 70 a , 70 b , . . . 70 n ) measure motion or loads beyond one or more specified thresholds, then controller 60 may enter a shock control mode. Otherwise, controller 60 may remain in a normal (or vibration) control mode. Threshold values may, for example, comprise values just above maximum amplitudes expected during normal vehicle operation. Exemplary acceleration profiles for “shock” events may be approximated by pulses such as, but not limited to: (a) triangle, (b) half-sine, (c) square, and (d) combinations thereof.
- pulses such as, but not limited to: (a) triangle, (b) half-sine, (c) square, and (d) combinations thereof.
- a vibration mode module 624 may control the VPEA 30 so as to minimize the vibrational motion (e.g., absolute motion or relative motion) of vehicle seat 20 , or to minimize the motion of a body part of the occupant (e.g., head, hands, chest, pelvis, etc.). This may be done by isolating seat 20 and reducing motion transferred from the vehicle to seat 20 (e.g., reduce transmissibility).
- the inclusion of a stiffness element 50 allows the seat resonance to be reduced much lower than the vibration excitation input, thereby attaining vibration isolation.
- the inclusion of a variable stiffness element 50 allows the seat resonance to be tuned within a range.
- the VPEA 30 may then be controlled to actively or semi-actively reduce that resonance while maintaining high frequency isolation. Minimizing the motion of the occupant during normal operation will assist in enhancing comfort and reducing fatigue.
- controller 60 may utilize a “Skyhook” control method wherein, for example, the VPEA 30 is turned on to a desired force, F des , when the absolute velocity of the suspended mass (i.e., the vehicle seat), M, is the same sign as the relative velocity between the suspended mass and the base, (M-Mo).
- controller 60 may enter a secondary shock control mode.
- a shock mode module (of controller 60 ) may control the VPEA using any number of control strategies.
- the VPEA may be adjusted in real-time for optimal combination of occupant body loads and stroking distance to keep the occupant's body loads (e.g., pelvis, spine, neck, etc.) within acceptable limits.
- occupant weight data e.g., from a manual control, from one or more sensors, or a fixed occupant weight
- attitude measurements received as inputs to controller 60 may be utilized to determine load injury thresholds for various parts of the occupant's body (e.g., the pelvis, viscera, spine, neck, and head).
- the shock mode module 628 (of controller 60 ) may then determine load injury threshold values for various parts of the occupant's body by utilizing statistical data gathered from a range of body types to determine a correlation between a range of acceptable load limits for each body part and the provided weight value.
- Loads should be kept under injury threshold values for all body parts. Generally, because the lumbar spine tends take the brunt of the load, optimizing for the load injury threshold of the lumbar spine tends to be adequate to prevent injury to other body parts. However, in certain instances, other body parts (e.g., head, chest, etc.) may be of primary concern. As such, in various implementations, optimization may focus on just one body part, or on keeping loads under injury threshold values for the most injury-susceptible body part. Other optimization strategies may be implemented.
- the shock mode module 628 may, for example, determine a load injury threshold for one or more parts of the occupant's body by utilizing minimum load limits from the range of acceptable load limits corresponding to each body part. The shock mode module may then adjust the VPEA 30 in real-time such that actual loads experienced by one or more of the occupant's body parts are maintained at or below the determined load injury thresholds during the vehicle shock event. This may be accomplished, in one regard, by bringing the actual load experienced by the occupant's body part up to, but not in excess of, the determined load injury thresholds while minimizing stroking distance of the variable profile energy absorber 30 .
- the VPEA 30 may be controlled such that the force level is initially high and then lowered as the seat 20 strokes to offset the increasing spring force, thereby maintaining the total force transmitted to the occupant as substantially constant.
- Another possible operational configuration of the VPEA 30 is that it may be set in its off-state for load transmission levels assuming a preset weight value and preset shock event level.
- the VPEA may be powered continuously, prior to the occurrence of a shock event, to maintain force levels at a preset value, thereby reducing the time required for the system to adjust itself in response to a measured shock event.
- the VPEA 30 may be controlled such that the force level is initially high and then lowers as the seat strokes to offset the increasing spring force, thereby maintaining the total force transmitted to the occupant as substantially constant.
- VPEA may be set in its off-state for load transmission levels assuming a preset weight value and preset shock event level.
- the VPEA 30 may be powered continuously, prior to the occurrence of a shock event, to maintain force levels at a preset value, thereby reducing the time required for the system to adjust itself in response to a measured shock event.
- a permanent magnet may be included in the VPEA 30 to offer the potential for off-state bias operation.
- the controller 60 After recognizing through at least one sensor 70 a. . . n measurement that a first shock event has occurred, the controller 60 enters recoil/recovery mode to return the VPEA 30 to substantially its initial position.
- the recoil function returns the VPEA 30 to substantially its initial position after a first shock event quickly enough to perform its function for a subsequent shock event.
- the recovery function controls the recoil in such a way that the VPEA 30 does not experience an extensional end-stop impact, and so that the system does not oscillate undesirably.
- the controller 60 detects the occurrence of a first shock event (from a sensor), the magnitude of a second immediate shock event may be estimated based on prior collected sensor measurement data (e.g., severity of the first shock event).
- the controller 60 may communicate with the VPEA 30 via a control signal to mitigate the anticipated transmission of loads to the seat occupant at the predicted second shock level. This sequence may be repeated as needed. Once the occurrence of shock events has ceased, the controller 60 may then return the VPEA 30 to the primary operational mode for vibration isolation.
- the controller 60 may detect the occurrence of the first shock event (from a sensor 70 a - n ), based in part on at least one measurement received that exceeds a predetermined threshold value or other shock indication, and may then enter secondary mode to adjust the VPEA 30 in real-time via a control signal such that the variable profile VPEA 30 force level is initially high, but then lowers as the seat 20 strokes to offset increasing spring force, thereby maintaining the total force transmitted to the occupant low and nearest to constant as possible.
- the controller estimates the second immediate shock event is based on prior collected sensor measurement data, by which the VPEA is adjusted, after recovering substantially to its initial condition, to mitigate the transmission of loads to the seat occupant at the predicted shock level.
- the controller also has the ability to return to the operational mode for vibration isolation.
- the adaptive energy absorption system 100 performs repetitive energy absorption, recoil, and preset operations in response to multiple successive shock events.
- the VPEA 30 may be adjusted in real-time such that the load-stroke profile is optimally controlled to utilize the full stroke capability of the VPEA 30 , thereby minimizing loads imparted into the body.
- real-time environmental measurements may be used to tune the system to the harshness of each particular event.
- This approach provides an advantage over conventional seat energy absorption systems which tend to be tuned for a fixed shock level (thus, not optimally controlling body loads for other shock levels).
- an FLEA may be tuned for a specific sink rate (e.g., 30 ft/sec).
- the stroke would have to increase or the system may bottom-out, which may resulting in high loads being imparted into the occupant's spine.
- the sink rate was lower than the tuned value (e.g., 15 ft/s)
- the FLEA will stroke at an unnecessarily high load and would not utilize all of the stroke capability.
- a VPEA 30 can modify its load-stroke profile to optimize stroke and load imparted into the occupant for each individual shock event, ensuring that the full stroke is safely utilized while imparting the least possible amount of load into the occupant.
- the secondary shock mode module may adjust the VPEA 30 in real-time, based on the weight of the occupant and on real-time motion information received as inputs, so that an actual load experienced by a part of the occupant's body is minimized during the vehicle shock event by utilizing substantially an entire stroke of the variable profile energy absorber.
- EA energy absorbed
- EA energy needing to be absorbed
- F seat load
- S necessary stroke
- the energy absorbed is dependent upon the shock scenario.
- V velocity before impact
- M mass of the stroking portion of the laden seat
- controller 60 may use a biodynamic mathematical model (such as, for example, a lumped parameter model).
- FIG. 7 is an exemplary illustration of a control flow diagram for a system (and method) wherein controller 60 comprises a dual mode controller that utilizes a biodynamic model module 622 to estimate body loads/motion.
- controller 60 comprises a dual mode controller that utilizes a biodynamic model module 622 to estimate body loads/motion.
- the control flow of FIG. 7 is similar to that of FIG. 6 except that a biodynamic model module 622 is included.
- Biodynamic data corresponding to injury thresholds, along with other biodynamic data, may be stored in the biodynamic model module 622 (e.g., a look-up table) of controller 60 .
- the stored biodynamic data may comprise statistical data relating to injury criteria (e.g., acceptable load limits or “thresholds”)) for a range of body parts for a range of body types, including pelvis, viscera, spine, neck, and head. Other biodynamic data may be stored.
- the biodynamic model module 622 may automatically update parameters (e.g., mass, stiffness, damping, distributions, etc.) for the biodynamic model based upon occupant weight (either measured or manually set by weight indication mechanism 62 as described above) to estimate body loads/motion.
- the output of the biodynamic model module 622 is then provided to vibration mode module 624 and/or shock mode module 628 for processing using the control strategies described above (with regard to FIG. 6 ) for vibration isolation and shock mitigation.
- biodynamic model that may be utilized with the invention is disclosed in United States Patent Publication No. 20070278057 by Wereley et al. published Dec. 6, 2007, which has been incorporated herein by reference in its entirety.
- the biodynamic model was described in an article identified as: Choi et al., Mitigation of biodynamic response to vibratory and blast-induced shock loads using magnetorheological seat suspensions, Proceedings of the Institution of Mechanical Engineers, Part D (Journal of Automobile Engineering), June 2005, vol. 219, no. D6, p. 741-53 (Professional Engineering Publishing).
- FIG. 8 is an exemplary illustration of a control flow diagram for a system (and method) wherein controller 60 comprises a dual mode controller that utilizes gain scheduling via a gain scheduling module 629 to control the VPEA 30 .
- controller 60 comprises a dual mode controller that utilizes gain scheduling via a gain scheduling module 629 to control the VPEA 30 .
- biodynamic data corresponding to occupant mass, motion, loads, etc. are provided to a gain schedule module 629 (from the biodynamic data module 626 ).
- gain schedule module 629 controls the VPEA 30 (using the control strategies described above) for vibration isolation or shock mitigation.
- controller 60 may comprise a single-mode controller that may operate only in a mode to mitigate injury to an occupant of vehicle seat 20 when an occurrence of a vehicle shock event (or other extreme motion event) is determined. Any of the foregoing control strategies as described for shock mitigation may be implemented in any such implementations.
- the seats 20 may be bench seats, or alternatively, bucket seats, platform seats, or any other form of seat.
- the system may adapt to the weight of the total occupants in the seat, regardless of the number of occupants (e.g., the multiple occupant seat may have only one occupant or any number up to a fully loaded multiple occupant seat.
- the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.
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